1. Technical Field
Example embodiments relate to an organic semiconducting polymer and an organic electronic device including the polymer.
2. Description of the Related Art
Polyacetylene is a conjugated organic polymer with semiconducting properties. The development of polyacetylene, consequently, has spurred an interest in organic semiconductors. Organic semiconducting materials may provide certain benefits over inorganic semiconducting materials. For example, organic semiconducting materials may be synthesized using various synthesis methods and may be manufactured into fibers or films with relative ease. Additionally, organic semiconducting materials may have improved flexibility, improved conductivity, and/or reduced fabrication costs compared with inorganic semiconducting materials. As a result, research regarding the incorporation of organic semiconducting materials into functional electronic/optical devices has been increasing.
Organic semiconducting materials have been used in organic thin film transistors (OTFT). Generally, a channel layer of an organic thin film transistor is formed of inorganic semiconducting materials (e.g., silicon), which involve higher temperature vacuum processes and higher costs. However, organic semiconducting materials are being used more as displays become larger, cheaper, and more flexible. Unlike silicon thin film transistors, the semiconductor layers of organic thin film transistors may be formed using atmospheric pressure wet processes, thereby avoiding the use of plasma-enhanced chemical vapor deposition (PECVD) processes. Additionally, OTFTs may be manufactured using roll-to-roll processes and may utilize plastic substrates, if suitable or necessary for the intended application, thereby reducing the cost of fabricating the semiconductor device.
Lower molecular or oligomeric organic semiconducting materials, including melocyanine, phthalocyanine, perylene, pentacene, C60, and thiophenoligomer, have been researched by those skilled in the art. For example, a charge mobility of 2.0 cm2/Vs and a current on/off ratio of 109 or greater has been reported with higher purity pentacene monomeric crystals, as a part of an attempt to increase the charge mobility by controlling the substrate temperature or deposition ratio, thereby increasing the size of thin film crystalline forms or the size of crystalline particles.
Thiophene-based polymers have also been used in OTFTs. The use of thiophene-based polymers may be beneficial with regard to processing, because lower cost, larger-surface processing may be possible with a solution-based processing (e.g., printing technology). Additionally, OTFTs using a thiophene-based polymer may be fabricated at room temperature, thus providing potential energy and cost savings. A polymer-based OTFT device using a polythiophene material may have a current mobility of 0.01˜0.02 cm2/Vs. However, commercialization of OTFTs may require a relatively high current on/off ratio and charge mobility, thus requiring current leakage in the off state to be reduced.